April 23, 2012 -- The shingles vaccine is "generally safe and well tolerated," according to a study of nearly 200,000 patients.

Shingles, or herpes zoster, is a painful rash caused by reactivation of chickenpox virus that has remained dormant in the body. Up to 1 million Americans, more than half of whom are 60 or older, are diagnosed with shingles every year, the researchers write.

Researchers analyzed data of 193,083 vaccinated patients aged 50 or older for certain side effects that could be related to the shingles vaccine.

The researchers found no increased risk in the first six weeks after vaccination for stroke, heart disease, infections of the brain or spinal cord or other brain diseases, Bell's palsy, or Ramsay-Hunt syndrome, which can occur when the virus that causes shingles affects the facial nerve near an ear.

An increased risk of allergic reaction was found in the first week after receiving the shingles vaccine.

A majority of these reactions involved an inflammatory response at the injection site, involving symptoms such as redness, swelling, and mild pain.

'Reassuring' Study

"We didn't find an increased risk of serious side effects, so that's reassuring," says researcher Hung Fu Tseng, PhD, MPH, a researcher with the Kaiser Permanente Southern California Department of Research & Evaluation "I think that's the main message of this study."

Zostavax, Merck's shingles vaccine, was licensed by the FDA in 2006 for use in healthy people 60 and older. In March 2011, the FDA also approved the vaccine's use for people in their 50s.

So far, the CDC's Advisory Committee for Immunization Practices(ACIP) has recommended Zostavax only for people 60 and older, says Eddy Bresnitz, MD, Merck's global medical director for adult vaccines.

Because the ACIP hasn't recommended the vaccine for people in their 50s, only about a third of insurance plans will cover it for that age group, Bresnitz says.

Halfway to 2020 Goal

In 2010, only about 14.4% of U.S. adults 60 and older reported having received the shingles vaccine, although that's up from 10% in 2009, according to the CDC. The "Healthy People 2020" goal is 30%, Bresnitz says.

Safety concerns haven't been an issue for patients, Tseng says. Reimbursement and the requirement that Zostavax be stored in a freezer have been among the main obstacles to wider use, he says.

Pediatricians typically have freezers in their offices to store childhood vaccines such as the one for chickenpox, Bresnitz says. But that's not always the case for doctors who only treat adults, he says, and they might not want to invest in one just for the shingles vaccine. Instead, Bresnitz says, doctors can refer patients seeking Zostavax to any of the more than 12,000 U.S. pharmacies participating in the Merck Adult Vaccination Program.